The present invention relates to a drive for an elevator installation.
An elevator installation consists of a car for reception of goods or persons to be transported and a counterweight, or a second car, which are connected together by way of supporting and driving means via a drive. The drive of the elevator installation in that case has the object of driving the driving and supporting means and thus an alternate raising and lowering of the car and the counterweight.
The drive consists of the principal components of a drive pulley, a motor and a brake. The drive pulley receives the supporting and driving means and transmits drive forces to the supporting and driving means by way of a mechanically positive or friction couple. The motor for its part drives the drive pulley, and the brake brakes the drive pulley.
A drive for an elevator is shown in the European patent document EP 1 400 477 in which a motor drives drive pulleys by means of a drive shaft and the drive pulleys are braked by a brake. The drive pulleys are in that case, in a preferred form of embodiment, arranged between the motor and the brake unit. The drive pulleys drive flat belts. This allows use of small drive pulley diameters. The drive can thereby be of small and compact construction.
However, the illustrated drive has disadvantages:
I. A conventional motor such as, for example, an asynchronous motor generates heat which has to be conducted away at least partly via the drive shaft. The drive pulleys thereby significantly heat up and this impairs the service life expectation of conventional supporting or flat belts.
II. The mounting and, in particular, the alignment of the drive pulley axle relative to the running direction of the supporting and driving means is costly.